Currently, the public switched telephone network (PSTN) is employable to transport voice and data traffic between two locations. As the traffic on the PSTNs has increased, alternatives have been sought for transporting voice data between caller locations. As such, new voice-over-packet (or cell) network architectures are being considered for public telecommunications networks that will require large scale signaling gateways to connect data centric networks to the existing circuit switch network infrastructure. To provide for the voice-to-packet conversion various types of media gateways are distributed along the edges of the PSTN and a packet based network. The media gateways may be controlled by a number of call/media control computers at one or more centralized locations.
Specifically, these call/media computers may be employed to provide class 4 and class 5 voice switching services via protocols that control various types of media gateways. The call/media control computers centrally act as service switching points (SSP) wherein command signals for transmitting the voice data from one location to another is received via the SS7 messaging network. As is well known, common channel signaling networks, such as the SS7 signaling networks use dedicated channels to pass digital messages between systems for call set-up, call control, call routing and other functions. These dedicated signaling channels are part of a network that is separate from the network that carries the actual voice and data signals. SS7 network is a separate switching system which is used for voice or data calls. The SS7 network is used to route control information wherein whenever two switches or elements have to pass call control information during or prior to a phone call they pass as data via the SS7 signaling network.
There are three basic types of network node elements in a SS7 network. One of them is the SSP, which may be a central office switch or a tandem switch. The second principal node element is the service control point (SCP). An SCP acts as a database query server for the rest of the network. For example, an SCP may be used in such applications as translating ported telephone numbers, routing 800 calls, tracking roamers in a cellular network, and alternate billing service/line indication database services which provide operator type services. The third principal node element is the signal transfer point (STP). An STP is essentially a packet switch that routes the messages from SSPs and SCPs to SSPs and SCPs. The topology of the network is such that STPs are typically employed in a related pair configuration at geographically separate locations. In connection with a mated pair of STPs will be a designated set of SSPs and SCPs.